CZ287146B6 - Aqueous composition of sizing agent being represented by cyclic dicarboxylic acid anhydride or alkyl ketene dimer and use of such composition - Google Patents

Abstract

In the present invention there is disclosed an aqueous composition of a sizing agent being represented by cyclic dicarboxylic acid anhydride or alkylketene dimer and being intended for use as a supply and surface sizing agent in paper, carton or cardboard manufacture. This composition comprises amorphous polymer being represented by amphoteric starch or amphoteric polymer based on acrylamide and polymeric compound of aluminium being represented by polyaluminium chloride, polyaluminium acetate, polyaluminium chloride containing sulfate, polyaluminium sulfate or a mixture or a condensate of cationic dicyanidamide resin and polymeric compounds of aluminium, whereby such compositions of the alkylketene dimer sizing agent contain 5 to 30 percent by weight alkylketene dimer, 1 to 35 percent by weight amphoteric polymer based on the alkylketene dimer weight and 0.1 to 10 percent by weight polymeric compound of aluminium, computed as {Ali2Oi3} and based also on the alkylketene dimer weight. Further the sizing agent compositions based on cyclic dicarboxylic acid anhydride contain 0.1 to 5 percent by weight cyclic dicarboxylic acid anhydride and 0.1 to 10 percent by weight polymeric compound of aluminium, computed as {Ali2Oi3} and based also on the cyclic dicarboxylic acid anhydride weight, whereby the amphoteric polymer is present in an amount corresponding to weight ratio of the cyclic dicarboxylic acid anhydride to the amphoteric polymer ranging from 1 : 1 to 1 : 4.

Description

An aqueous sizing composition which is a cyclic dicarboxylic acid anhydride or an alkyl ketendimer, and the use of the composition

Technical field

The invention relates to sizing compositions reacting with a synthetic water-based acid which is an alkyl ketene dimer or a cyclic dicarboxylic acid anhydride, and more particularly to such compositions comprising an amphoteric polymer and a polymeric aluminum compound.

BACKGROUND OF THE INVENTION

Alkyl ketendimers (AKDs) and cyclic dicarboxylic acid anhydrides, in particular alkenylsuccinic anhydride (ASA), are widely used for sizing paper, which sizing increases paper and liquid resistance at all, at neutral or alkaline pH. Said compounds react with cellulose and bind directly to the hydroxyl groups in said cellulose. Commercially used products are usually stabilized with cationic screws, which contribute to the creep reassurance in the raw material. Also, retention agents and other chemicals are also typically added to the feedstock to enhance retention and sizing. It is known, for example, to use sizing agents in combination with aluminum compounds. Often, small amounts of alum are added to the ASA emulsion, either as an emulsion or as a separate raw material, the primary task of which is to improve the problems associated with fixing the sizing agent on the fibers when papimizing. Japanese Patent Application JP No. 84-199900 discloses the manufacture of sized papim by adding cationic AKD dispersion, highly cationized starch and a water-soluble aluminum salt to the feedstock. German Patent Application No. 4090740 discloses a process which incorporates an aluminum compound and a cationic dispersing agent, such as cationic starch, into polymer AKD dispersions. Due to the high cost of the ketone dimer, AKD-based sizing compositions are very expensive, which implies that development will focus in particular on the production of dispersions that will provide the best sizing effects with the lowest amount of AKD. Other requirements to be met by these dispersions are stability and sufficiently high solids contents.

SUMMARY OF THE INVENTION

As already mentioned, the water-based cyclic dicarboxylic acid ketendimers or anhydrides of the present invention containing both an amphoteric polymer and a polymeric aluminum compound have a very good sizing effect at a low sizing agent content due to their good yield. the retention of this sizing agent and also because they contribute positively to the general retention of fibers and fillers and that they have dewatering effects in papime production. In addition, they exhibit good effects in the presence of retention / drainage systems which operate on the basis of anionic inorganic colloids such as silicon colloids and cationic polymers and which are generally added separately to the composition.

Accordingly, the invention relates to an aqueous sizing composition which is a cyclic dicarboxylic acid anhydride or an alkyl ketene dimer, characterized in that it comprises an amorphous polymer which is an amphoteric starch or an amphoteric acrylamide-based polymer and a polymeric aluminum compound which is a polyaluminium chloride, polyaluminium acetate, polyaluminium chloride containing sulfate, polyaluminium sulfate or a mixture or condensate of a cationic dicyandiamide resin and a polymeric aluminum compound, wherein the alkyl ketimer dimer compositions comprise from 5 to 30 wt. % alkyl ketene dimer, 1 to 35 wt. % of an amphoteric polymer, based on the weight of the alkyl ketene dimer, and 0.1 to 10 wt. polymeric aluminum compound, calculated as Al ₂ O ₃ and also by weight

% Of alkyl ketene dimer, and cyclic dicarboxylic acid anhydride-based sizing compositions comprise 0.1 to 5 wt. % cyclic dicarboxylic acid anhydrides and 0.1 to 10 wt. a polymeric aluminum compound calculated as Al ₂ O ₃ and also based on the weight of the cyclic dicarboxylic acid anhydride, wherein the amphoteric polymer is present in an amount corresponding to the weight ratio of the cyclic dicarboxylic acid anhydride to amphoteric polymer of 1: 1 to 1: 4.

Two types of sizing agents are known per se. The cyclic dicarboxylic acid anhydrides can be characterized by the general formula

where

R ₂ represents a dimethylene or trimethylene radical and R] is a hydrocarbon group having more than 7 carbon atoms and may be alkyl, alkenyl, aralkyl or aralkenyl group. The cyclic dicarboxlylic acid anhydrides which are widely used commercially are alkyl- and alkenylsuccinic anhydrides (ASA) and in particular isooctadecenyl succinic anhydride.

Alkylketendimeiy have the general formula:

where

R 1 and R ₂ are hydrophobic hydrocarbon groups having about 6 to 30 carbon atoms and which are usually alkyl groups having 12 to 20 carbon atoms, for example hexadecyl and actadecyl groups.

As used herein, the term "amphoteric" refers to polymers containing both anionic and cationic groups. Amphoteric starch is preferred, and in this case, the anionic groups may be, for example, phosphates, phosphonates, sulfates, sulfites, or carboxylic acid groups, and preferably phosphate groups. The cationic groups are tertiary amino groups or quaternary ammonium groups. The ratio between the number of anionic and cationic groups in the starch is in the range of 0.025: 1 to 90: 1 and preferably in the range of 0.4: 1 to 40: 1. Any starch containing both of these types may be used for the aqueous compositions of the invention groups. Thus, the starch itself can be obtained from potatoes, corn, wheat, tapioca, rice, waxy maize, and the like. Anionic groups in the starch may be a natural component thereof and / or may be introduced into the starch by chemical processing. Especially suitable is the ingestion of cationized potato starch since the natural potato starch contains a considerable amount of covalently bonded phosphoric acid monoester groups.

The amphoteric polymer may also be an acrylamide-based amphoteric polymer that is water-soluble and wherein the major monomer unit is acrylamide and / or methacrylamide. These polymers may have a molecular weight of from about 10,000 to about 1,500,000, suitably from about 300,000 to about 5,000

800,000. Amphoteric acrylamide-based polymers can be prepared by introducing ionic groups into a polymer that contains (meth) acrylamide as the main component. The cationic groups can be introduced in various ways, for example by the Hofmann degradation and the Mannich reaction, and the anionic groups can be introduced, for example, by hydrolysis or a sulfomethylation reaction. An amphoteric acrylamide-based polymer can also be prepared by copolymerizing (meth) acrylamide and monomer mixtures of both anionic and cationic monomers.

Both the amphoteric and the polymeric aluminum compounds are present in the compositions of the invention. It is to be expected that there will be some interaction between the ionic groups contained in the amphoteric polymer and between the polymeric aluminum compounds, which will contribute to good stability of said compositions and good sizing retention in said feedstock.

Preferred sizing agents are ketendimei. Aqueous AKD dispersions containing both an amphoteric polymer and a polymeric aluminum compound provide a very good sizing effect at a low AKD content, have sufficient stability and can be produced for commercial use with a very high dry matter content. In addition, said dispersions are effective in the presence of retention / drainage systems which operate on the basis of combinations of anionic inorganic colloids, such as silicon-based colloids, and cationic polymers. It will also be appreciated that such dispersions as such may contribute to improving dewatering and general retention of fibers and optical fillers.

Polymeric aluminum compounds are those based on aluminum, hydroxy, and anions, which are designated as base and form polynucleic complexes in aqueous solution. Polymeric aluminum compounds such as polyaluminium chloride and sulphate-containing polyaluminium chloride are well known compounds and, when used in conjunction with paper, are used, inter alia, in papim sizing using a natural resin to fix the natural resin with which it forms an aluminum-resin complex.

Examples of suitable compounds include polymeric aluminum compounds having the general formula

AUOH ^ Xj ^ where

X is a negative ion, such as chloride or acetate, where _m and n are positive integers so that 3n_m is greater than 0. Preferably X is Cl 'and such polymeric aluminum compounds are known as polyaluminium chlorides (PAC). The polyaluminium chlorides may also contain anions of sulfuric acid, orthophosphoric acid, polyphosphoric acid, chromic acid, dichromic acid, silicic acid, citric acid, carboxylic acids or sulfonic acids.

The basicity of the above polymeric aluminum compounds is defined as the m / 3nx 100 ratio. The basicity suitably lies in the range of 10 to 90% and preferably in the range of 20 to 85%.

The most suitable polymeric aluminum compounds used for the composition of the invention are polyaluminium chlorides, polyaluminium chlorides containing sulfate and polyaluminium sulfates. As examples of polyaluminium sulfates, mention may be made of those having the general formula

Al (OH) _x (SO ₄ ) _y (H ₂ O) _n where

X has a value of 1.5 to 2.0, y has a value of 0.5 to 0.75, x + 2y = 3 and z = 1.5 - 4, suitably 1.5 - 3.0. The term "polymeric aluminum compounds" as used herein also includes mixtures and co-condensates of cationic dicyadiamide resins and polymeric aluminum compounds. Such products are described in European patent application EP 320986.

-3GB 287146 B6

An example of a commercially available polymeric aluminum compound is Ekoflock, manufactured and sold by Aka Nobel AB in Sweden. In this case, the basicity is about 25% and the sulfate and aluminum content is about 1.5% by weight. respectively. 10% by weight, the aluminum content being calculated as the Al 2 O 3 content. Dominating complex in aqueous solutions of ₃ A1 (OH) ₄ ⁵⁺ which is at a greater or lesser dilution converted to A1 _I3 O ₄ (OH) ₂₄ ^7+. Other examples of commercially available compounds are sulfate-free Sachtoklar, sold by Sachtleben Chemie in Germany, sulfate-containing WAC, sold by Atochem in France, the highly basic polyaluminium chloride compound Locron, sold by Hoechst AG in Germany, poly (hydroxyaluminum) sulfate Omniklir, sold by OmiK in USA, Niaproof, which is aluminum hydroxyacetate, sold by Niacet in the USA, and Alzofix based on polyaluminium chloride and dicyadiamide, sold by SKW Trostberg, Germany.

The ketendimer dispersions according to the invention preferably contain 5 to 20 wt. amphoteric polymer, based on the weight of the ketendimer. The polymeric aluminum compound is present in a relatively high amount, preferably in an amount of 1 to 6% by weight, calculated as the amount of Al ₂ O ₃ , based on the amount of ketendimer. Despite the high amount of aluminum compound, the dispersions of the invention exhibit good stability. The dispersions of the invention may contain about 5 wt. % to about 30 wt. AKD, preferably in the range of 10 wt. % to 20 wt.

The ketendimer dispersions of the present invention can be prepared by mixing an aqueous solution of an amphoteric polymer and AKD wax at a temperature in the range of about 55 ° C to about 95 ° C and homogenizing the mixture at the above temperature and pressure of about 5 to 50 MPa. The emulsion thus obtained, having a droplet size of from about 0.3 to about 3 µm, is subsequently rapidly cooled and a polymeric aluminum compound is suitably added during or after cooling. In addition to the three essential ingredients mentioned above, other ingredients such as anionic surfactants such as sodium lignosulfonate and fillers such as urea and urea derivatives may be incorporated into the dispersions.

The cyclic dicarboxylic acid anhydrides are liquid at room temperature. An emulsifier is usually present in commercial ASA products. Aqueous cyclic dicarboxylic acid anhydride compositions are emulsions, wherein the compositions of the invention can be prepared by mixing liquid acid anhydrides with an amphoteric polymer solution, wherein a polymeric aluminum compound is present in the solution. The solution should be kept at 20 ° C. Suitably, the cyclic dicarboxylic acid anhydride compositions of the invention comprise an acid anhydride and an amphoteric polymer in a weight ratio of 1: 1 to 1: 4. The ratio of polymeric aluminum compound to cyclic dicarboxylic acid anhydrides corresponds to the above ratio of polymeric aluminum compound to ketendimer dispersions. ASA emulsions are usually manufactured directly in a paper mill, where they are subsequently used as sizing agents in paper making, either as surface sizing agents or as sizing agents applied to the mass. Generally, the amount of acid anhydride is from about 0.1 to 5% by weight.

The compositions of the present invention are used in conventional manner to produce papim. In the manufacture of papime, paperboard and cardboard, they can be used either as surface sizing or added to the raw material. The invention further relates to a process for the production of papim, wherein the surface sizing agents or sizing agents added directly to the mass are cyclic dicarboxylic acid anhydride compositions or alkyl ketendimers containing an amphoteric polymer and a polymeric aluminum mixture as described above. When sizing in the mass, it is suitable to add said composition to 0.197 to 7.874 kg of AKD or cyclic dicarboxylic acid anhydrides per tonne of dry matter of said raw material, ie fibers and optical fillers, the dose being dependent in particular on the quality of the papim used.

-4GB 287146 B6

The invention will be further illustrated by the following examples, which are only illustrative in nature and are not intended to limit the scope of the claims. The percentages given in the examples are by weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

The ketendimer dispersions according to the invention were prepared as follows: 70 g of potato starch, cationized to the 0.042 substitution step, were mixed with 450 g of AKD-wax and about 2340 g of water containing 15 g of sodium lignosulfonate at 75 ° C, followed by mixing The mixture was homogenized at the indicated temperature and pressure of 20 MPa and subsequently quenched. A polymeric aluminum compound was added during cooling. To obtain dispersion 1a), 120 g of sulfate-containing polyaluminium chloride, designated Ekoflock, supplied by Eka Nobel AB, was added. In order to obtain dispersion 1b), 168 g of polyaluminium sulfate, designated as Omniklir and supplied by Omni-Kem, USA, were added corresponding to 2.8% Al 2 O 3. To obtain dispersion 1c), 150 g of Alzofix P (dicyandiamide-polyaluminium condensate) from SKW Trostberg in Germany, corresponding to 2.8% Al 2 O 3, were added.

Example 2

Paper sheets were made from standard raw materials, such as bleaching kraft pulp (48% birch, 32% pine and 20% calcium carbonate) at pH 8.0 using a standard SCAN-C23X method for laboratory scale. The Cobb values measured according to the Tappi T 441 OS-63 standard are shown in the table below. In these tests, the dispersion 1a) of the invention was observed with a reference dispersion, Ref., Containing cationic waxy maize starch and the same polymeric aluminum compound as in dispersion 1a), wherein said starch and said polymeric aluminum compound were present in the reference dispersion in the same amounts as in the case of dispersion 1a).

AKD Cobb 60 dispersion number kg / tg / m ²

la) 0.3 33 la) 0.4 25 la) 0.5 23 la) 0.6 22nd Ref. 0.3 65 Ref. 0.4 30 Ref. 0.5 25 Ref. 0.6 25

As can be seen from the above table, AKD dispersions containing a polymeric aluminum compound in which starch is represented by amphoteric starch are far more effective than products containing starch having only cationic groups.

Example 3

The sizing effect of dispersions 1b) and 1c) was compared and determined in the same manner as in the previous Example 2, the results obtained being recorded in the following table.

-5GB 287146 B6

Dispersion no. AKD kg / t Cobb 60 g / m ² (lb) 0.3 34 (lb) 0.4 28 (lb) 0.5 24 (lb) 0.6 23 lc) 0.3 30 lc) 0.4 24 lc) 0.5 24 lc) 0.6 23 Example 4

In this example, the edge penetration values for a 35% H ₂ O ₂ solution were determined using the so-called "Edge Wick Test". The tests were performed on CTMP pulp, from which paper having a basis weight of 150 g / m ² was produced at pH 7.6. In all cases, in addition to the AKD dispersion, alum, a polyamidoamine wet-strength resin, a silica sol-dewatering-retention system and a cationic starch were separately added to the material in addition to the AKD dispersion. A comparison was made between dispersion 1a) according to the invention and a standard AKD dispersion containing a cationic starch obtained from waxy maize, Ref. 1, and a dispersion corresponding to 1a) but not containing a polymeric aluminum compound, Ref. 2.

Dispersion AKD kg / t h ₂ o ₂ kg / m ² la) 1 3.35 la) 1.5 2.58 la) 2 1.49 la) 3 1.57 Ref. 1 1 3.95 Ref. 1 1.5 3.20 Ref. 1 2 2.33 Ref. 1 3 2.14 Ref. 2 1 3.88 Ref. 2 1.5 3.06 Ref. 2 2 2.30 Ref. 2 3 2.14

As can be seen from the above table, the dispersions of the invention clearly yield a better sizing effect compared to a standard product. It is also evident that this effect is not entirely dependent on the type of starch, but is also dependent on the combination of the amphoteric starch and the polymeric aluminum compound.

Example 5

In this example, the same feedstock was tested as in the previous examples, and the drainage tests were conducted in the presence of a commercial retention and drainage system having the designation Compozil and including inorganic silica (Si-sol) and cationic starch (CS), added to the feedstock separately. Tests were performed using this system in the presence of various ketendimer dispersions, and the drainage effect was measured using the Canadian Standard Freeness (CSF) Test, a common method used to characterize the drainage ability of SCAN-C. 21: 65. For test-0, the raw material without the addition of a retention and drainage system (R-Dsystem) or AKD dispersion had a drainage capability of 310 ml CSF. It was tested

The dispersions 1a) and 1b) according to the invention and their dewatering capacity were compared with a reference dispersion, i.e. a standard AKD dispersion containing a cationic starch obtained from waxy maize.

Dispersion no. AKD kg / t CSkgPt RD systém Si-sol kg / t CSF ml - 4 1 550 - - 6 1 580 - - 8 1 575 la) 1 4 1 580 la) 1 6 1 615 la) 1 8 1 590 (lb) 1 4 1 570 (lb) 1 6 1 600 (lb) 1 8 1 590 Ref. 1 4 1 540 Ref. 1 6 1 575 Ref. 1 8 1 570

As can be seen from the above tables, the dispersions of the invention provide an improved drainage effect, while the reference dispersions contribute to a slight deterioration of this drainage effect.

Claims (12)

An aqueous sizing composition which is a cyclic dicarboxylic acid anhydride or an alkyl ketene dimer, comprising an amphoteric polymer which is an amphoteric starch or an amphoteric acrylamide-based polymer and a polymeric aluminum compound which is a polyaluminium chloride, polyaluminium acetate, sulphate-containing polyaluminium chloride or a mixture or condensate of a cationic dicyadiamide resin and a polymeric aluminum compound, said alkyl ketimer dimer compositions comprising 5 to 30 wt. % alkyl ketendimer, 1 to 35 wt. % of an amphoteric polymer, based on the weight of the alkyl ketene dimer, and 0.1 to 10 wt. % of a polymeric aluminum compound, calculated as Al 2 O 3 and also based on the weight of the alkyl ketendimer, and the sizing compositions based on cyclic dicarboxylic acid anhydrides contain 0.1 to 5 wt. % cyclic dicarboxylic acid anhydrides and 0.1 to 10 wt. a polymeric aluminum compound calculated as Al 2 O 3 and also based on the weight of the cyclic dicarboxylic acid anhydride, wherein the amphoteric polymer is present in an amount corresponding to the weight ratio of cyclic dicarboxylic acid anhydride to amphoteric polymer of 1: 1 to 1: 4. 2. The aqueous composition of claim 1 wherein the amphoteric polymer is amphoteric starch. Aqueous composition according to claim 2, characterized in that the ratio of amphoteric starch, indicating the ratio between the number of anionic groups and cationic groups, is in the range of 0.025: 1 to 90: 1. Aqueous composition according to claim 2 or 3, characterized in that said amphoteric starch is cationized potato starch. Aqueous composition according to claim 1, characterized in that the polymeric aluminum compound is a polyaluminium chloride, a polyaluminium chloride containing sulfate, polyaluminium sulfate or a mixture or condensate of a cationic dicyandiamide resin and a polymeric aluminum compound. Aqueous composition according to claims 1, 2, 3, 4 or 5, characterized in that the polymeric aluminum compound is a polyaluminium chloride containing sulfate, polyaluminium sulfate or a mixture or condensate of a cationic dicyandiamide resin and a polymeric aluminum compound. Aqueous composition according to claim 5, characterized in that the polymeric aluminum compound is present in an amount of from 1 to 6% by weight, calculated as Al 2 O 3 and based on the weight of the sizing agent. Aqueous composition according to any one of the preceding claims, characterized in that said sizing agent is an alkyl ketene dimer. Aqueous composition according to claim 8, characterized in that said amphoteric polymer is present in an amount of from 5 to 20% by weight, based on the weight of the ketendimer. Aqueous composition according to claim 8 or 9, characterized in that the amount of ketendimer is from about 10 to 20% by weight. Use of the aqueous composition according to any one of the preceding claims 1 to 10 as a stock sizing agent in the manufacture of papim, cardboard or paperboard. Use of the aqueous composition according to any one of the preceding claims 1 to 10 as a surface sizing agent in the manufacture of papim, cardboard or paperboard.